How Can We Be Sure of the Diagnosis of Chronic Pancreatitis?

Chronic pancreatitis has a wide spectrum of symptoms and severity, making it difficult to diagnose. While the advent of numerous radiographic, endoscopic and functional testing has certainly advanced our ability to reliably diagnose chronic pancreatitis, it can, at times, complicate diagnosis in an age of unclear interpretation of results. Given that this condition is not curable and treatment modalities are aimed at delaying progression and controlling symptoms, providers must be certain prior to diagnosing (“labeling”) patients with chronic pancreatitis. Diagnosis should follow a progressively invasive approach in a patient with a suspicious clinical presentation and risk factors that raise his or her pre-test probability of disease. Currently, the most widely used risk factor classification system is the Toxic Idiopathic Genetic Autoimmune Recurrent Obstructive system or TIGAR-O, and one approach for diagnosis follows the STEP-wise (survey tomography endoscopy pancreas function) algorithm.

Initial evaluation of a patient presenting with recurrent pancreatitis and abdominal pain should be a thorough office evaluation during which providers screen for weight loss, diabetes, jaundice and anorexia followed by laboratory testing of amylase, lipase, metabolic panel, fecal elastase-1, or serum trypsin and review of any previous imaging.

Once this is complete, imaging is appropriate pancreatitis. starting with an abdominal contrast-enhanced computerized tomography (CT). This technique relies on changes to pancreatic parenchyma that are consistently seen in more advanced cases and may be absent in early chronic pancreatitis. Changes classically seen with CT include pancreatic calcifications, parenchymal atrophy or fibrosis, and dilation of the main pancreatic duct.2 In addition to visualizing these changes, CT is also helpful in detecting complications of chronic pancreatitis such as pseudocysts, venous thrombosis and pancreatico-pleural fistulas. Finally, a CT should be performed in all patients to rule out a mass or malignancy.

In patients with equivocal CT scans, magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP) and secretin enchanted MRCP (sMRCP) should be obtained in cases where a high clinical suspicion for chronic pancreatitis remains. The advantage of an MRI is the increased sensitivity to pancreatic ductal abnormalities, as these changes typically precede glandular atrophy and are not typically seen using CT. In addition, these modalities evaluate for depressed signal intensities within the gland indicative of parenchymal atrophy, and when sMRCP is utilized, the evaluation of pancreatic duct compliance can be assessed. Definitivediagnosis of chronic pancreatitis can be made with MRI/MRCP when ductal irregularities are observed in both the main pancreatic duct as well as side branches. Cambridge-type grading criteria have yet to be established for MRCP but are generally used. Endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) are more invasive measures that are at times used to assist in the diagnosis of chronic pancreatitis. The advantage of EUS is the superb parenchymal and ductal visualization of the pancreas. EUS criteria (standard or Rosemont) have been established for chronic pancreatitis. These include both parenchymal features (hyperechoic foci and strands, lobular contour, cysts) as well as ductal features (main duct dilation, irregularity, hyperechoic margins, visible side branches and stones). At least five of these standard EUS criteria need to be met prior to definitively diagnosing chronic pancreatitis (grade 3 recommendation). Fewer than five criteria can be seen in normal, asymptomatic patients and carry unclear significance. These cases should be correlated with imaging, pertinent risk factors as well as the patient’s clinical presentation.

ERCP has historically been used as a last line diagnostic tool in the work up of chronic pancreatitis once other modalities have been exhausted. It has been replaced by MRI imaging. Its diagnostic utility lies in defining the main pancreatic duct as well as its side branches. These changes are graded based on the Cambridge classification system. Two major limitations for use of ERCP in diagnosing chronic pancreatitis include procedural complication(such as acute pancreatitis) as well its inability to visualize the pancreatic parenchyma.

Pancreatic-function tests (PFTs) are defined as either direct or indirect. Indirect pancreatic-function tests (serum trypsinogen, fecal elastase, fecal fat measurements) are often obtained at the start of the work up of chronic pancreatitis and are more likely to detect advanced cases of chronic pancreatitis. Direct pancreatic-function tests which utilize secretin or cholecystokinin (CCK) stimulation, can help detect cases of chronic pancreatitis prior to development of exocrine gland dysfunction or clarify subtle radiographic abnormalities. Its greatest use is as an adjunct diagnostic tool when the diagnosis is not definitive with CT or MRI. It is best at ruling out chronic pancreatitis in patients with chronic abdominal pain.


When the diagnosis remains unclear, pancreatic function tests can be helpful to rule out chronic pancreatitis.


In summary, the diagnosis of chronic pancreatitis can be elusive in early disease. The evaluation should follow a combined approach from a noninvasive to a more invasive diagnostic algorithm (STEP-wise). Radiologic testing should be obtained to assess definitive changes consistent with chronic pancreatitis as well as ruling out a mass. In equivocal cases, one should progress to endoscopic approaches (such as EUS) to evaluate for moderate to significant changes. When the diagnosis remains unclear, pancreatic function tests can be helpful to rule out chronic pancreatitis. Further studies of biomarkers (cytokines, MRNA and proteins) are needed to diagnose early chronic pancreatitis before definitive changes develop.

Dr. Anaizi has no conflicts to disclose.

Dr. Conwell has no conflicts to disclose..

References

1.American Pancreatic Association Practice Guidelines in Chronic Pancreatitis: evidence-based report on diagnostic guidelines. Conwell, Darwin L et al. Pancreas, 2014 Nov;43(8):1143-62..

2.Chronic Pancreatitis: Making the Diagnosis. Conwell, Darwin L. et al. Clinical Gastroenterology and Hepatology, Volume 10, Issue 10, 1088 – 1095.

3.Ketwaroo G, Brown A, Young B, Kheraj R, Sawhney M, Mortele KJ, Najarian R, Tewani S, Dasilva D, Freedman S, Sheth S. Am J Gastroenterol. Defining the accuracy of secretin pancreatic function testing in patients with suspected early chronic pancreatitis. 2013 Aug;108(8):1360-6. DOI: 10.1038/ajg.2013.148. Epub 2013 May 28.

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